Many applications exist for high induction magnetic materials.
Desirable magnetic properties of glassy metal alloys for applications such as magnetic shields have been disclosed by E. M. Gyorgy in Metallic Glasses, p. 275, American Society for Metals, Metals Park, 1976.
The effect of a superposed alternating field on apparent magnetic permeability and hysteresis loss of magnetic materials was considered in T. Spooner, Phys. Rev. 25, 527 (1925). Spooner investigated one percent silicon steel punchings and found that for small induction values the apparent permeability was increased by a d-c magnetizing force.
B. S. Evenden, D. R. Stone and N. A. Anstey in Seismic Prospecting Instruments, Vol. 2, disclose employing a d-c magnetic field or a high frequency bias field for improving the recording characteristics of tape heads.
David Cohen in Applied Physics Letters, 10, 67 (1967) discloses enhancement of ferromagnetic shielding against low-frequency magnetic fields by impression of an alternating magnetic field of a constant amplitude.
W. Albach and G. A. Voss in Z. f. Agnew Physik, 9, 112 (1957) disclose increasing the magnetic shielding of dynamo sheet metal by pre-excitation with alternating magnetic fields.
Donald F. Eldridge in IRE Transactions on Audio, September-October 1961, page 155, discussed the mechanism of A-C-biased magnetic recording.
H. P. Pratt in U.S. Pat. No. 2,026,060 discloses placing a magnetic shell in a magnetic field to enhance its electromagnetic shielding capacity.
Marvin Camras in Proceedings of the IRE 50, 751 (1962) discusses some of the explanations and theories with regards to the playback process in magnetic recording including a-c biasing.
Marvin Camras in U.S. Pat. No. 2,351,004 discloses a system for linearly impressing magnetic variations on a completely demagnetized steel wire.